Heretofore, as for this type of equipment, there has been provided load storing equipment of the closed type as found, e.g., in Japanese Laid-open Patent Application No. 3-177208(1991).
This conventional arrangement includes a load storing section (shelving) defining a plurality of vertically disposed storage spaces in a box-like main body, with the front surface of said section being opposed to the passage. The storing section is opened in its front surface opposed to the passage and its opposite rear surface, with a filter covering the rear surface, and an air feed passage is defined rearwardly of the filter and between the latter and the main body. Installed in the lower region inside the main body is a blower communicating in its delivery side with said air feed passage and in its suction side with the passage.
A carrying in-and-out device is installed in the passage and comprises a floor rail, a carriage supported and guided on said floor rail through wheels and adapted to travel in a given path extending along the front surface of the load storing section, a support frame erected from the carriage at one end as seen in the direction of the given path, a lifter guided by a guide body installed in the support frame, and a load holding device for transfer installed on said lifter.
In the conventional load storing device described above, the air discharged from the discharge section of the blower moves upward in the air feed path and-through the individual filters to appear as highly clean air, which is fed to the load storing section through the rear surface, so that the load storing section is maintained highly clean by the clean air flowing from the rear surface to the front surface. The clean air passing through the load storing section in this manner flows downward in the path and is drawn again by the fan for circulatory use. The carrying-in-and-out device performs carrying in and out of loads with respect to the intended storage spaces by a combination of the traveling movement of the carriage, the upward and downward movements of the lifter and the transfer movement of the load holding device.
According to the conventional arrangement described above, the erected single support frame is rectangular in cross section and its transverse thickness and longitudinal width are increased from the standpoint of strength, with the result that the clean air passing through the load storing section flows against the support frame and is thereby disturbed to produce large swirls, thus producing an agitated state in the passage, scattering dust particles to cause the latter to adhere to the loads.
Further, the carrying in-and-out device has its overall length increased by the presence of the support frame which has its transverse thickness increased by the reception of all (almost all) of the lifter driving device, while when the load holding device is placed in opposed relation to the end of the load storing section, the support frame and other parts are positioned outwardly of the ends of the shelves. As a result, the box-like main body has to be formed large in size including the shunting space (dead space) for the support frame; thus, the number of stored loads in the spaces, i.e., the storage efficiency is lowered and the clean operation cost is increased.
Further, since the lifter is supported in a cantilever manner by the support frame, the lifter movement and warehousing and unwarehousing operations are attended with sway or the like movement and are unstable. On the other hand, if a pair of transversely spaced support frames are disposed, said shunting space is needed on each side of the given path.
The said lifter, as seen, e.g., in Japanese Laid-open Patent Application No. 63-180610(1988), is operatively connected to a lifter driving device disposed in a post through a slit formed in said post. And by the forward and reverse rotation of this lifter driving device, the lifter is moved upward and downward as it is guided by the guide body disposed in the post.
In this case, if the cross sectional area of the support frame is minimized, the connecting structure (lifting body) which operatively connects the lift to the lifter driving device, and the counter weight for balancing the upward and downward movements will be densely disposed in the support frame. Therefore, when the connecting structure and counter weight are moved upward and downward, a pumping phenomenon of air develops in the support frame, whereby the foul air in the support frame will be blown out into the cleaned main body through the slit.
Further, according to the conventional arrangement found in said Japanese Laid-open Patent Application No. 3-177208(1991), the dead space defined in the lower region of the load storing section for disposing a blower has a substantial height and hence leads to enlarging the shelves in their entirety and raising the level of the lowermost step in the load storing section to lower the storage efficiency.